Hhhow dddo I cccon-ccccont-ccccccontrol mymy st-st-stuttering?

Based upon the way you wrote your question, I will assume that your stuttering consists of repetitions of sounds and syllables as well as prolongations (sustaining a sound). There are several techniques that can help you. If your stutter is as severe as your question makes it seem, you should seek therapy from a Speech-Language Pathologist in your area. Visit www.asha.org/proserv to find one who is certified.

Now, here are some things to try:
1. Slow your speech rate
2. Train yourself to barely tap your articulators, meaning that when you say "stutter" your tongue does not push hard against the top of your mouth for the /t/, but instead barely contacts it at all.
3. Try to ease into what you are saying. If you anticipate a stutter on a particular word, slow down and ease into it, slow-motion like.
4. Practice fake stuttering. When you anticipate a stutter on a particular word, think about it and force yourself to stutter. For example, if you expect that "memory" will be a tough one, say it like this: "I have an excellent mem-mem-mem-mem-mem-memory." Overdo it a bit, so that you remember that it's a false stutter. This may actually help you to learn how to recover more easily from real stutters when they occur.

My best advice remains to seek the direct services of a Speech-Language Pathologist. If you are fortunate enough to still be in school, consult your school SLP for a free evaluation. If not, speech therapy can get expensive, but the reward may greatly outweigh the cost.
Good luck!